Nanofilaments of catalytic materials for chemical process improvements

ABSTRACT

A Haber-Bosch process including the steps of providing a reactor having a substrate with catalyst filaments formed thereon. The catalyst filaments are formed of a metal including iron. A nitrogen compound and hydrogen are injected into the reactor such that at least a portion of the nitrogen compound and hydrogen contact the catalyst filaments. The nitrogen compound and hydrogen are reacted with the catalyst filaments at a temperature of less than about 600° F. and a pressure of less than about 2000 psig.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/151,560 filed on Jan. 9, 2014, which application was a continuationof U.S. application Ser. No. 13/722,613 filed on Dec. 20, 2012, whichapplication was a continuation-in-part of U.S. application Ser. No.12/726,106, filed on Mar. 17, 2010, which claims the benefit under 35USC §119(e) of U.S. provisional application Ser. No. 61/160,949 filedMar. 17, 2009, all of which this application claims priority to andwhich are incorporated by reference herein in their entirety.

FIELD AND BACKGROUND OF INVENTION

The present invention generally relates to catalytic processes and inparticular embodiments, catalyst shapes and structures to enhancecatalytic activity.

Catalytic processes are used in enumerable chemical processes, with someestimates suggesting that 90% of all commercially produced chemicalproducts involve catalysts at some stage of their manufacture. Examplesinclude catalytic cracking in the petroleum refining industry, catalyticoxidation in many large-scale chemical production methods, highlyspecialized catalytic reactions in fine chemical production, catalytichydrogenation in the food processing industry, polymer production, andreduction of pollutants in transportation and industrial emissions.

Several factors affect the efficiency of catalytic processes, includingoptimizing reactant exposure to the catalyst, activation energy of thecatalyst, minimizing the catalyst's degradation, and improving theregeneration of catalyst when required. Improvements in one or more ofthese factors would be beneficial across a broad spectrum of catalyticprocesses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a very basic reactor system.

FIG. 2 schematically illustrates a slightly more complex reactor system.

FIGS. 3A to 3D illustrate different substrates with catalyst formedthereon.

FIGS. 4A to 4D illustrate a series of steps used in one method offorming catalyst on a substrate.

FIGS. 5A and 5B schematically illustrate the orientation of catalystsubstrate elements in two different reactor arrangements.

FIG. 6 schematically illustrates the reactor system utilized in oneexperimental example.

FIG. 7 schematically illustrates the reactor system utilized in anotherexperimental example.

FIG. 8 illustrates the hydrocarbon distribution from an experimentalexample.

FIG. 9 illustrates a test reactor device for another experimentalexample.

FIGS. 10A and 10B schematically illustrate petroleum cracking andreforming processes.

FIG. 11 schematically illustrates a dry reforming process.

FIG. 12 schematically illustrates a catalytic converter system.

FIG. 13 schematically illustrates a lithium-ion cathode embodiment.

FIG. 14 schematically illustrates a lithium-air cathode embodiment.

FIG. 15 schematically illustrates a Haber-Bosch process embodiment.

FIG. 16 schematically illustrates a fuel cell embodiment.

FIG. 17 illustrates another alternate method of forming the catalystmicro-structures on a substrate.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

One embodiment of the invention is a Fischer-Tropsch process (FTP)wherein a gaseous carbon compound and hydrogen are injected into areactor such that at least a portion of the carbon compound and hydrogencontact a catalyst material and are reacted with the catalyst (often atabove ambient pressure and temperature) in order to form hydrocarbonchains. As suggested in FIG. 1, such a process would include a reactor 2which is fed from a carbon compound source 3 and a hydrogen source 4.Catalyst substrate elements 5 would be positioned in reactor 2 and havethe catalyst formed thereon. The carbon compound and hydrogen will passthrough the reactor 2 and react with the catalyst to produce ahydrocarbon output product 6. Many variations of this basic process arepossible. For example, FIG. 2 illustrates a preheater 10 positionedbefore reactor 2 and a condenser 12 positioned thereafter. The preheater10 would raise the temperature of the carbon compound and hydrogen fromtheir initial temperatures to a temperature closer to that desired atthe reactor input. Condenser 12 would operate to condense gaseoushydrocarbons, remove water 7 from the output product 6, and to provide afinal de-watered liquid hydrocarbon product 8.

The carbon compound may take many different forms depending on the typeof catalyst employed, the end product desired, and the particularprocess parameters. In many FTP systems, the carbon compound willtypically be CO, but could be other carbon compounds. The hydrogen istypically in the form of molecular hydrogen (H₂), but could be otherhydrogen containing compounds. The catalyst substrate elements 5 maytake enumerable shapes or forms. FIG. 3A illustrates a flat platestructure 15 while FIG. 3B illustrates a rod structure 16 acting as asubstrate. Other non-limiting examples of substrate shapes/structuresinclude tubular substrates, either straight or curved (e.g., spiraled),and washer-shaped substrates. Typically, the substrates will be formedof metal or have a metal coating applied to the surface of the substrateonto which the catalyst is formed. Certain embodiments may includeconductive metals such as aluminum, cobalt, iron, copper, platinum,palladium, rhodium, ruthenium, chromium, nickel, other noble metals,other transition metals, other conductive metals/alloys. Substrates maytake irregular forms such as a comparatively planar surface which has alarge number of micro-structures formed thereon. In one example, themicro-structures are a field of micro-needles (defined below) which thenhave a catalyst material sputtered on as a thin film. In certainembodiments, nominal dimensions for such substrate micro-structures mayrange from about 5 nanometers to about 1 micron.

In one embodiment, the substrate is an aluminum foil type material 18which is rolled to provide concentric layers of substrate material (seeFIG. 3C) having catalyst micro-structures 17 formed thereon. In anotherembodiment (FIG. 3D), the substrate will be non-uniform with bearingsurfaces 36 and protected recessed surfaces 37. The catalystmicro-structures 17 could be formed on the recessed surfaces 37 in alocation protected from mechanical engagement with other surfaces whilebearing surfaces 36 would contact the walls of the reactor or othercatalyst substrate elements. In many embodiments, the substrate elementis substantially nonporous, meaning that the substrate is sufficientlynonporous that under given reaction pressures and flow rates, thereactants will flow around and past the substrates (thus contactingmicrostructures on the substrate surface) rather than through thesubstrate material.

In certain embodiments, catalyst will be formed on the substrate aselongated micro-structures. One version of these micro-structures have awidth of less than about 1 um and include a crystal structure havingsubstantially no grain boundaries. In other versions, themicro-structures may also contain grain boundaries, either engineeredand controlled for specific effects or simply allowed as inherent partof a particular manufacturing process. Although the size is greatlyexaggerated, FIGS. 3A and 3B suggest how these elongatedmicro-structures 17 (or “micro-needles” 17) may be formed on asubstrate. Although the width or diameter of micro-needles 17 in manyembodiments will range anywhere from a few nanometers to about 1 um (orany sub-range therebetween), certain width ranges for micro-needles 17include between about 10 nm and about 500 nm or between about 20 nm andabout 100 nm. Micro-needles 17 are elongated in the sense that they willhave a length at least five times their diameter, and more commonly alength at least 5 times to about 10,000 times their diameter (or anysub-range there between) or alternatively, about 10 um to about 5millimeters in length (or any sub-range there between).

As used herein, a crystal structure having no grain boundaries means allcrystals in the structure have a predominantly uniform orientation in asingle crystalline plane. One example of how the orientation of thecrystalline plane may be defined is the Miller Index. Thus, thecrystalline plane may be defined as [100], [111], etc. Such a crystalstructure has substantially no grain boundaries when the mis-orientationbetween grains is at a relatively low angle, for example less thanapproximately 10 to 15 degrees. In certain embodiments, the minimizationof grain boundaries is accomplished by limiting the micro-needlediameter to about 100 nm or less.

In many embodiments, the micro-needles will be formed on the substrateor a relevant portion of the substrate (i.e., not necessarily the entiresubstrate surface) at a given pore density. Pore density is defined asthe total area of micro-needles (i.e., the sum of cross-sectional areaof the needles) attached to the substrate divided by the substratesurface area over which needles are distributed. In one embodiments, thepore density is approximately 50%, but in other embodiments the poredensity could range from about 10% to about 90% (or any sub-range therebetween). Likewise, less common embodiments could exist with poredensities around the 1% to 5% range or the 90% to 100% range.

The catalyst materials employed will often depend on the type of FTPbeing utilized. In certain embodiments, the catalyst material will be atleast one of cobalt, iron, nickel, or ruthenium. The micro-needles willoften be formed completely of one element. Alternatively, themicro-needles could be a non-catalyst material coated with a catalystlayer. Other embodiments could include micro-needles formed from a firstcatalyst material (e.g., cobalt) and capped with a section of a secondcatalyst material (e.g., ruthenium). The catalyst materials could alsobe alloys whose compositions include cobalt, iron, or ruthenium togetherwith other elements or compounds. Four particular embodiments forconstructing catalyst structure could include: 1) simple electroplatingof one metal as one crystal; 2) one metal in one or more crystal planesfor a desired effect; 3) two or more metals all electroplated insuccessive layers with each successive layer essentially “capping” theprevious layer and leaving all previous material exposed; and 4)deposition of another material on top of existing needles (or otherstructures) with the intention of completely covering theneedle/structure. The deposition technique described in (4) could be byevaporation (thermal or electron beam), sputtering, reactive sputtering,self-assembled monolayers, multiple layers from a polyelectrolytemulti-layer technique, or chemical vapor deposition.

Numerous processes may be used to form the micro-needles described aboveonto a substrate. In one embodiment suggested in FIG. 4A to 4D, thesubstrate 20 (e.g., a plate seen from the side) may be a conductivematerial such as aluminum, copper, titanium, nickel, iron, chromium,tungsten or an alloy of these materials. A non-conductive layer 21 isformed or is allowed to form on the surface of the substrate 20 (FIG.4B). For example, where the substrate 20 is aluminum, an aluminum oxidecoating may be formed on substrate 20. In one embodiment, the aluminumoxide coating is formed through an anodization process. Prior toanodization, the substrate is typically cleaned in either a hot soakcleaner or in a solvent bath and may be etched in sodium or similarcompounds. The anodized aluminum layer is grown by passing a directcurrent through an electrolytic solution (e.g., sulfuric acid), with thealuminum object serving as the anode. Example voltages may range from 1to 300 V DC, although more typically fall in the range of 15 to 21 V.Example anodizing currents vary with the area of aluminum beinganodized, but typically may range from 0.3 to 3 amperes of current persquare decimeter (20 to 200 mA/in²).

Anodizing may be performed in an acid solution which slowly dissolvesthe aluminum oxide. The acid action is balanced with the oxidation rateto form a coating with microscopic pores 22 suggested in FIG. 4C.Conditions such as electrolyte concentration, acidity, solutiontemperature, and current are controlled to allow the formation of aconsistent oxide layer and may be used to control the size of the pores.Anodizing at lower temperatures tends to decrease the density of thepores; the pore and ultimately needle/micro-structure nominal diameteris decreased and the aluminum oxide mass is increased. Increased currenttends to increase the diameter of the pores in the aluminum oxide andthe resulting needle/structure density. As explained in more detailbelow, the pore size is configured to obtain the desired diameter of themicro-needles. The thickness of the anodized layer 21 may vary with oneexample being an approximately 50 um thick aluminum oxide coating.

As suggested in FIG. 4D, one embodiment involves placing the substrate20 having anodized layer 21 and micro-pores 22 in a solution containingcatalyst ions. In the example of FIG. 4D, the catalyst ions are cobaltions formed by dissolving CoNO₃ in an aqueous solution in a (molar)concentration range of about 0.05 to about 2.0. Alternatively thecatalyst ions may be formed by dissolving CoSO₄ in an aqueous solutionin a (molar) concentration range of about 0.05 to about 6.0. FIG. 4Dillustrates the cathode of DC voltage source 27 being connected tosubstrate 20 and the anode 29 being positioned in the catalystcontaining solution. As a voltage is applied between substrate 20 andanode 29, elongated cobalt structures (micro-needles 28) will grow inthe pores 22. It will be understood that the size of the pores 22 willgovern the diameter of the micro-needles 28. Factors affecting growth ofthe catalyst needles include temperature of the solution, strength ofthe electric field, solution chemistry, and spatial orientation of theelectrodes (e.g., distance apart). Typically, the further the anode isfrom the substrate, the greater the tendency for the micro-needles toform in an elongated manner. In the embodiment of FIG. 4D, theelectrolyte temperature may range between about 10° C. and about 50° C.;the current density may range between about 1 to 500 mA/cm2 with 50mA/cm² being a typical value when electroplating in pulse-reverse mode;and the anode 29 is positioned at least about 2 cm to about 30 cm fromthe surface of the substrate 20. Of course, these are merely exampleparameters and those skilled in the art will recognize innumerablealternative parameters and techniques.

In other embodiments, sources of the Co or Fe ions might be Co(NO₃)₂,FeCl₂, and other similar compounds. In certain embodiments, the electriccurrent may alternate or be pulsed. In an alternate embodiment, themicro-needles will be formed in the presence of a magnetic field inorder to aid in the uniform orientation of the crystal lattice as themicro-needles are grown. As one example, a magnet 26 may be positionedbelow substrate 20 in order to create a magnetic field having anorientation suggested by magnetic flux lines 30. As an alternative toapplying the magnetic field during micro-needle growth, the fully formedmicro-needles could be subject to a magnetic field and heat treatmentprocess to effect a desired dipole alignment. Nevertheless, it should beclear that the invention also includes micro-needles grown in theabsence of any applied magnetic field.

While the above examples form the micro-structures through aelectroplating technique, numerous other processes could be used to formthe micro-structures, non-limiting examples of which include lowpressure chemical vapor deposition (LPCVD), plasma enhanced chemicalvapor deposition (PECVD), or sputtering.

Once the catalyst micro-needles are formed on a substrate, one or moresubstrate elements having the micro-needles may be positioned within areactor. While certain orientations of the substrate elements in thereactor may produce a more efficient reaction, the exact orientation ofthe substrate elements may vary significantly from embodiment toembodiment. As suggested by FIG. 5A, a plate substrate 15 could beoriented such that the surfaces with micro-needles 17 are perpendicularto the overall flow direction of the reactants. While hidden from view,these plate substrates 15 would have micro-needles formed on the front(shown in FIG. 5A) and back (view hidden in FIG. 5A) sides. Althoughspacing of plate substrates 15 is greatly exaggerated, FIG. 5A suggestshow the plates could be positioned to direct flow around the plates tomaximize contact with the catalyst micro-needles. Regarding rodsubstrates 16, these could be positioned with their long axis parallelto the overall flow direction of reactants as suggested by FIG. 5B.Likewise, the substrates seen in FIGS. 3C and 3D would be positionedwith their long axes parallel to the overall direction of reactant flow.

The reactor parameters may differ considerably depending on variablessuch as the type of catalyst employed, the input reactants and the finalproduct sought. As one nonlimiting example, where H₂ and CO are thereactants, cobalt micro-needles are positioned on rod substrates in thereactor, and the intended product is diesel type hydrocarbons (i.e.,ranging from approximately C₁₀H₂₂ to C₂₅H₅₂), then the reactor mayoperate in temperature ranges of approximately 300° F. to 500° F. andpreferably about 400° F., while the pressure in the reactor ismaintained in a range of about 100 psig to 500 psig and preferably about400 psig. Example reactant flow rates would include about 75 to about1000 standard cubic centimeters per minute (SCCM) for CO and about 150to about 2000 SCCM for H₂. The ratios ranged from 1.0 to 2.0 H₂/CO.

In an alternate Fischer-Tropsch process embodiment, the reactorcomprises substrate elements having elongated micro-structures of atleast one of cobalt, iron, or ruthenium. The carbon compound andhydrogen are fed into the reactor and reacted with the catalyst at atemperature (i.e., the average internal temperature of the reactor)between about 80° F. and about 200° F. (or any sub-range therebetween).In another variation of this embodiment, the carbon compound andhydrogen are reacted with the catalyst at a temperature between about90° F. and about 150° F. In any of the FTP embodiments described herein,the carbon compound (e.g., carbon monoxide) and hydrogen may be suppliedat a mass ratio ranging from about 1:1 to about 1:3 and more preferablyabout 1:1 to about 1:2. Generally the reactor temperature will vary withpressure. At lower temperatures, the reactor pressure may be betweenabout 0 and 5 psig. More commonly the reactor pressure may be betweenabout 5 and 50 psig (or any sub-range therebetween). However, otherembodiments may run at a reactor pressure of between about 0 and 400psig (or any sub-range therebetween).

In another alternate embodiment, the reactor may be a conventional plateframe heat exchanger. In this type of heat exchanger, there aretypically two alternating chambers or pathways, usually thin in depth,separated at their largest surface by a corrugated metal plate. Theplates may be spaced by sealing gaskets which are placed into a sectionaround the edge of the plates. In an alternate embodiment the plates arewelded together and no gaskets are required. The plates are oftenpressed to form troughs at right angles to the direction of flow of theliquid which runs through the channels in the heat exchanger. Thesetroughs are arranged so that they interlink with the other plates whichforms the channel with narrow gaps on the order of millimeters (e.g.,1.3-1.5 mm) between the plates.

The catalyst micro-needles will be formed on the plate surfaces of thepathway which is exposed to the reactants. A temperature control(typically cooling, but also heating in other embodiments) fluidcirculates through the other pathway. In a modification of thisembodiment, the reactant(s) may be mixed in a diluent. For example,where CO and H₂ are the reactants, these reactants could be mixed decaneor hexane as diluents prior to entering the reactor.

A further embodiment seen in FIG. 10A is a reactor column 70 whichgenerally comprises a riser tube 71 with a temperature control coils 72contacting the outside of riser tube 71 and micro-structures 73 formedeither directly on the inside surface of riser tube 71 or on separatesubstrate elements positioned in the riser tube 71. Reactants will entervia input path 74, contact the catalyst structures 73 and product(s)exit via exit path 75. In one example, reactor column 70 may be used ina fluid catalytic cracking process, where preheated high-boilingpetroleum feedstock (at about 315 to 430° C.) consisting of long-chainhydrocarbon molecules is injected into the catalyst riser where it isvaporized and cracked into smaller molecules of vapor by contact withthe catalyst micro-structures. In such embodiments, the catalyst may beplatinum or iron coated with platinum.

Alternatively, the reactor column 77 in FIG. 10B could be employed inpetroleum reforming process which converts petroleum refinery naphthas,typically having low octane ratings, into high-octane liquid productswhich are components of high-octane gasoline. The liquid feed is joinedby a stream of hydrogen-rich gas and the resulting liquid-gas mixture ispreheated by flowing through a heat exchanger. The preheated feedmixture is then totally vaporized and heated to the reaction temperature(495 to 520° C.) before the vaporized reactants enter the reactor.Although FIGS. 10A and 10B schematically illustrate catalystmicro-structures 73 on the sides of the reactor columns, it will beunderstood that the catalyst could be positioned on any substratestructure located anywhere in within the column.

Another embodiment suggested in FIG. 11 involves dry reforming ofmethane to produce syngas. This reactor 80 includes a temperaturecontrol mechanism 81. Reactor 80 could be any conventional reactor suchas the plate frame reactor or one of the tubular reactors describedabove. Temperature control mechanism 81 could be heating/cooling coils,fluid exchange conduits, or any other conventional temperature controlmethods. A substrate surface 82 within reactor 80 will include catalystmicroneedles 83. In a dry methane reforming embodiment, the catalystwould be nickel microneedles, e.g., solid nickel structures orstructures coated with nickel. The inputs or reactants in thisembodiment will be CO₂ and CH₄ while the output products would bepredominately H₂ and CO and unconverted CO2 and CH4.

FIG. 12 illustrates a reactor type which could serve as a catalyticconverter in an automobile exhaust system. Catalytic converter 85 maygenerally comprise a reactor body containing a catalyst substrate andcatalyst microneedles formed on the substrate. In one embodiment, thesubstrate elements comprise a plurality of rods positioned parallel tothe flow path of the reactor body. Typically, the input reactants willbe automotive exhaust gases such as CO, C_(n)H_(y), and NO_(x) and theoutputs are CO₂, O₂, and N₂. Certain embodiments may contain only onecatalyst type in the reactor. In other embodiments, the reactor may havea first set of substrate elements 88 with microneedles formed of areduction catalyst and a second set of substrate elements 89 with ofmicro-needles formed of an oxidation catalyst. Non-limiting examples ofreduction catalyst include platinum and/or rhodium and oxidationcatalyst include platinum and/or palladium.

FIG. 13 illustrates an embodiment wherein the microneedles form part ofan lithium-ion anode. The lithium-ion battery 90 includes battery body91 having an anode 92, a cathode 93, and electrolyte 94. The cathode isgenerally one of three metal oxide materials: a layered oxide (such aslithium cobalt oxide), one based on a polyanion (such as lithium ironphosphate), or a spinel (such as lithium manganese oxide). Theelectrolyte is normally a lithium salt in an organic solvent. Onetypical example is a mixture of organic carbonates such as ethylenecarbonate or diethyl carbonate containing complexes of lithium ions.These non-aqueous electrolytes generally use non-coordinating anionsalts such as LiPF6, LiAsF6, LiClO4, LiBF4 and lithium triflate. Oneembodiment of the anode 92 is conductive metal having micro-needles 95formed thereon with a carbon layer 96 subsequently formed on themicro-needles 95. In one preferred embodiment micro-needles 96 arecopper. One example method of applying a carbon layer to themicro-needles is using a plasma enhanced chemical vapor depositiontechnique to produce a harder, more diamond-like carbon layer. Anotherexample uses a low pressure chemical vapor deposition technique toproduce a less hard graphite-like carbon layer.

FIG. 14 illustrates an embodiment wherein battery 100 comprises Li metalanode 101 in LiPF₆ electrolyte 102. The cathode is formed of aperforated metallic membrane 103 with a PTFE membrane 105 which allowsO₂ to escape the battery but prevents the migration of moisture (H₂O)from contacting the battery electrolyte. In preferred embodiments,perforated metallic membrane 103 is a then plate of either Co, Au, or Niwith 10 um to 1 mm pores formed thereon. In these embodiments, Co is onepossible catalyst for micro-needles 104. During discharge, lithiumcations flow from anode 101 through an electrolyte 102 and combine withoxygen at the cathode to form lithium oxide Li₂O or lithium peroxideLi₂O₂; thereby inducing the flow of electrons from the battery's anodeto the cathode through a load circuit. The micro-needles catalyze thecombining of Li₂ and O₂ during discharge and catalyze the disassociationof these molecules during charging.

FIG. 15 illustrates a reactor 111 that could be employed in aHaber-Bosch process 110. Reactants N2 and H2 are fed into high pressurereactor body 111 where the reactants contact micro-structure catalystformed on substrate elements 112. In one embodiment, the N2 source issimply the surrounding atmosphere. The output containing ammonia andunreacted N2 and H2 are fed to cooler/condenser 113 which allows removalof ammonia and return of unreacted gases back the input of reactor body111. In this example of the Haber-Bosch process, the catalystmicro-structures are formed of iron or alternatively iron with osmiumtips or layers. Example pressure ranges within reactor 111 may be about0 psig to about 1000 psig (or any sub-range therebetween).

A still further embodiment in FIG. 16 schematically represents fuel cell115. Fuel cell 115 generally comprises hydrogen diffusion plate 116 andoxidant diffusion plate 117 with proton exchange membrane 119 positionedin between. Both diffusion plates 116 and 117 will have micro-needlecatalyst structures 118 positioned therein. In FIG. 16, the catalystmetal from which the micro-needles are formed is preferably platinum.Within hydrogen diffusion plate 116 the catalyst micro-needles catalyzethe disassociation of protons from the hydrogen and in oxidant diffusionplate 117 the combination of O₂ with hydrogen to form water.

Another method of forming the catalyst micro-structures is suggested byFIG. 17. In this embodiment, the catalyst micro-needles ormicro-filaments are formed in a process that generally includes the stepof forming an anodized aluminum oxide (AAO) layer on the substratelayer. The embodiment of FIG. 17 illustrates a substrate 150, aconduction layer 151, an AAO layer 152, and catalyst filaments 153formed through the AAO layer 152 and extending beyond the AAO layer 152.In the particular embodiment of FIG. 17, the substrate is formed of anonconductive material. Nonlimiting examples of such nonconductivematerials include, ceramics, polymers, and oxide coating on a conductingsubstrate, and concrete. The nonconductive material may also includesemi-conductive materials such as silicon or silicon based compounds. Inmany embodiments, the non-conductive material will have a resistivity ofgreater than about 0.15 ohm-cm. As described above, in many embodiments,the substrate material 150 will be substantially nonporous.

In FIG. 17, a conduction layer 151 is shown formed on substrate 150.This embodiment of conduction layer 151 is typically formed of agenerally conductive material, commonly having an electricalconductivity of at least 1,000,000 Ω ⁻¹·m⁻¹, and more particularly inthe range of metals such as copper (59,170,000 Ω ⁻¹·m⁻¹), aluminum(37,450,000 Ω ⁻¹·m⁻¹), titanium (1,852,000 Ω ⁻¹·m⁻¹), or chromium(8,000,000 Ω ⁻¹·m⁻¹). In preferred embodiments, the conduction layer 151is formed of a material which is capable of withstanding the anodizingenvironment and the process conditions under which the catalyst willultimately be used. Non-limiting examples of materials suitable forforming the conduction layer 151 include titanium and chromium andalloys thereof. The conduction layer 151 typically needs only have asufficient thickness or depth to form a conductive base for the formingof further metal layers on the conduction layer 151. For example, inmany embodiments, conduction layer 151 will be at least 5 nm thick andmore preferably at least 20 nm thick. Likewise in these embodiments, itmay be preferred that the conduction layer 151 be less than 200 nm thickand more preferably less than 100 nm thick. Conduction layer 151 may beformed on substrate 150 by any conventional or future developed process,including chemical vapor deposition, thermal or electron beamevaporation, or sputtering.

Once the conduction layer 151 has been deposited on the substrate, afilm of aluminum is formed on the conduction layer 151 which ultimatelyis anodized to form the AAO layer 152. In more general embodiments, thealuminum film will range from about 300 nm to about 2000 nm in depth,but could be any sub-range there between. In more preferred embodiments,the aluminum film will range between about 600 nm and about 800 nm.Again, the aluminum film may be formed on conduction layer 151 by anyconventional or future developed process, including chemical vapordeposition, thermal or electron beam evaporation, and sputtering,although preferred deposition processes include thermal evaporation orelectron beam evaporation.

In situations where the substrate 150 is itself formed of a sufficientlyconductive material, the conduction layer 151 may not be necessary andthe aluminum may be formed directly on the substrate. Example ofsufficiently conductive substrate materials include stainless steel,titanium, nickel, and chromium. Nevertheless, even when working with aconductive substrate, certain preferred embodiments will first form anon-conductive layer (e.g., ceramic layer or AAO layer) between theconductive substrate 150 and the conductive layer 151.

After the aluminum film is formed on conduction layer 151 (or directlyon a conductive substrate), it will be anodized to form the AAO layer152. The reaction between aluminum and oxygen reduces the density of thealuminum layer, causing the AAO layer to be thicker than the originalaluminum layer. In certain experiments, it was found that the AAO layerwas about 40% thicker than the original aluminum layer. As suggestedabove, the anodizing process will convert the aluminum layer into AAOlayer 152 and form pores in the AAO layer, with electrolyteconcentration, acidity, solution temperature, and voltage beingcontrolled to allow the formation of a consistent oxide layer and alsoto control the size and density of the pores. In certain preferredembodiments, the anodizing process will be controlled to produce an AAOlayer having pores ranging from about 10 nm to about 500 nm (or anysubrange therebetween) and more preferably between about 10 nm and about200 nm. In certain embodiments, the anodizing process is carried outuntil substantially all aluminum oxide within the pores is removed andthe pores expose the underlying layer. Similar to above embodiments, thepore density (i.e., the sum of cross-sectional area of the pores dividedby the substrate surface area over which the pores are distributed) mayrange anywhere from about 10% to about 95%. However, in more preferredembodiments, the pore density will be at least about 35%, and morepreferably at least about 40%, 50%, 60%, 70%, 80%, 90%, or 95%.

While many different anodizing conditions could be employed to producethe above pore size and density, one preferred anodizing technique,where the substrate was silicon with a titanium conduction layer, isanodizing with a 2% sulfuric acid solution at 0° C. in a two-stepprocess. The first anodizing step is carried out for about six minutesand the second anodizing step carried out for about 20 minutes. Bothsteps are conducted at 18V. A 3% phosphoric acid etch procedure may becarried out between the anodizing steps in order to remove the AAO layerformed during the first anodizing step. In certain embodiments, afterthe first anodization, the AAO is removed from the aluminum by a wetetching solution that has a high etch rate of AAO and a low etch rate ofaluminum. This leaves behind a semi-regular pattern of scallops. Then asecond anodization is performed on this semi-regular pattern whichassists the pattern to become more regular.

One preferred anodizing technique, where the substrate was silicon witha titanium conduction layer, is anodizing with a 2% sulfuric acidsolution at 20° C. in a three-step process. The first anodizing step isconducted at 12 volts with the substrate serving as the anode and withanother aluminum conductor serving as the cathode. This process iscontinued until there is a sharp drop in current. Typically the finalcurrent is approximately less than 100 micro amps per cm². At thispoint, a second phase of the process is conducted in which the polarityof the electrodes is reversed, where the substrate becomes the cathodeand the aluminum electrodes that had served as the cathodes become theanodes. The potential in this region is approximately 3.5 volts. Thisphase typically lasts less than one minute. The third phase reduces theapplied potential to 2.5 volts and typically lasts approximately 1minute.

In certain preferred embodiments. the aluminum layer is subject to theanodizing process until at least about 80%, or more preferably at leastabout 90%, or most preferably at least about 95% by weight of thealuminum layer is converted to the aluminum oxide (AAO) layer.

Once the anodizing process is complete, the substrate will have a seriesof catalyst material micro/nano-needles or filaments formed thereon. Inmany embodiments, the filaments will be formed by an electroplatingprocess where the filaments begin accumulating in the pores in the AAOlayer until the filaments generally have a length of between about 30 nmto about 5000 nm (or any subrange therebetween) beyond the AAO layer. Inone preferred embodiment, the lengths of the filaments will be betweenabout 500 nm and about 2500 nm. While various conventional and futuredeveloped electroplating processes may be used, one preferred process ispulse reverse electroplating, wherein the process includes cathodicpulses and anodic pulses, often with rest periods between the pulses. Asone nonlimiting example, the plating program consists of an 8 to 10 mscathotic pulse, a 2 ms anodic pulse, and a 500 to 600 ms rest period.The cathotic pulse is controlled with a current density of 50 mA/cm² anda compliance voltage of 10V. The anodic pulse is controlled at apotential of 3V and a compliance current density of 50 mA/cm². Thisprocess is continued until the filaments have reached the desiredlength, e.g., 3 hrs to electroplate filaments approximately 2000 nm inlength. Other examples may include processes where the pulse reverseelectroplating includes a current density of about 1 mA/cm² to 200mA/cm², a forward (cathotic) pulse time of about 1 ms to 500 ms, areverse (anodic) pulse time of about 1 ms to 500 ms, and a rest periodof about 10 ms to 2,000 ms. Alternatively, the pulse reverseelectroplating includes a current density of about 50 mA/cm² to 75mA/cm², a forward (cathotic) pulse time of about 4 ms to 120 ms, areverse (anodic) pulse time of about 1 ms to 30 ms, and a rest period ofabout 10 ms to 2,000 ms.

In certain embodiments, any remaining aluminum oxide from the initialAAO layer is removed during or after the electroplating process, butsuch removal of remaining aluminum oxide is considered optional in mostembodiments.

One characteristic of the filaments produced through this process is thefilaments tend to have a degree of twisting which enhances catalyticactivity by providing more active sites. One example includes thefilaments having radius of curvatures (in any direction) from thevertical centerline (or any other direction of filament growth) of 15 nmto 10 um. Another characteristic is that the overall filament array willhave a “packing density” or a given total mass of filaments per unit ofsurface area over which filaments are formed. In certain embodiments,the packing density will be between at least about 5 mg/cm² and about200 mg/cm². However, the packing density can also be at least any amountbetween 5 mg/cm² and about 200 mg/cm² (e.g., 20 mg/cm², 50 mg/cm². 100mg/cm², 150 mg/cm², etc.), or even outside the range of 5 mg/cm² andabout 200 mg/cm².

Although particular embodiments of the filaments may have lengthsgreater than 5000 nm, excessively long filaments may tend to coalesce,thereby reducing the number of catalytically active sites per gram ofcatalyst material. For example, it is believed that excessively longfilaments causes a reduction in the porosity at the upper end of thefilament array. In certain instances, the excessive lengths of thefilaments cause the upper ⅓ of the filament array to become less than10% porous by volume (or alternatively less than 5% porous, 3% porous,or 1% porous).

The filaments may be formed of any catalytic material. Preferredexamples include cobalt, iron, ruthenium, nickel, platinum, palladium,rhodium, osmium, vanadium, copper, aluminum, other transition elements,lanthanides, actinides, and fourth, fifth, and sixth period elements.The filaments could be formed completely of one element, could be anon-catalyst material coated with a catalyst layer, or could includefilaments formed from a first catalyst material (e.g., cobalt) andcapped with a section of a second catalyst material (e.g., ruthenium).The catalyst materials could also be alloys whose compositions includecobalt, iron, or ruthenium together with another elements or compounds.The nanowires may consist on alternating layers of different catalystmaterials

Substrates having the catalyst filaments described above may be used inany number of catalytic processes. A Fischer-Tropsch process is oneexample wherein substrate elements are positioned in a reactor and acarbon compound (as described above) and hydrogen are injected into thereactor such that at least a portion of the carbon compound and hydrogencontact the catalyst filaments (cobalt in this example). The reactantflow rates provided above form one appropriate example, but naturallythose skilled in the art will recognize many alternative reactant flowrates. The carbon compound and hydrogen are then reacted with thecatalyst filaments at a temperature of between about 100° F. and about500° F. and a pressure of less than about 500 psig. Alternatively, thetemperatures could be any sub-range between about 100° F. and about 500°F., e.g., about 150° F. and about 400° F. and the pressure could be lessthan 500 psig, e.g., under 400 psig, 350 psig, 300 psig, 250 psig, 200psig, 150 psig, 100 psig, or 50 psig. More preferably, the temperaturemay be between about 150° F. and about 300° F. and a pressure of lessthan about 200 psig.

The catalyst filaments described above may be utilized in other catalystbased reactions. For example, a Haber-Bosch process may be carried oututilizing iron catalyst filaments and H2, N2 reactants (i.e.,contemplating the reaction N2+3H2>2NH3). Pressure and temperature insuch a process would be under about 600° F., and under about 2500 psig,and more preferably under about 550° F., 500° F., 450° F., 400° F., 350°F., or 300° F. and under one of about 2000 psig, 1750 psig, 1500 psig,1250 psig, 1000 psig, 800 psig, 700 psig, 600 psig, or 500 psig.

One alternative embodiment is a Fischer-Tropsch process reactor surfacecomprising (a) a substrate element having a surface; and (b) a pluralityof elongated micro-structures of catalyst material attached to thesubstrate surface, the micro-structures comprising a width of less thanabout 1 um.

Another embodiment is a Fischer-Tropsch process reactor surfacecomprising (a) a substrate element having a surface; and (b) a pluralityof elongated micro-structures of catalyst material attached to thesubstrate surface, the micro-structures comprising a crystal structurehaving substantially no grain boundaries.

A still further embodiment (Embodiment A), is a catalytic reactorcomprising (a) an enclosed reactor body including at least one reactantentrance port and at least product exit port; (b) at least one substrateelement including a surface and being positioned within the reactorbody; and (c) a plurality of elongated micro-structures of catalystmaterial attached to the substrate surface, the micro-structurescomprising a width of less than about 1 um and a length at least fivetimes the width. Alternatives to Embodiment A could include (in thealternative): (i) a temperature control mechanism regulating processtemperatures of the reactor; (ii) a pressure control mechanismregulating process pressures of the reactor; (iii) the catalyst being atleast one of cobalt, iron, ruthenium, nickel, platinum, palladium,rhodium, or copper; (iv) the micro-structures comprising a crystalstructure having substantially no grain boundaries; (v) themicro-structures having a width of less than about 500 nm and a lengthat least ten times the width; (vi) the temperature control mechanismcomprising a cooling conduit which forms part of the substrate or uponwhich the substrate is positioned: (vii) the substrate elementconsisting substantially of a metal or a metal coated material; (viii)the substrate element being a plate member or a tubular member; (ix) thesubstrate element comprising a plurality of plates positioned in seriesin a flow path of the reactor body; (x) a first plurality ofmicro-structures comprising a reduction catalyst and a second pluralityof micro-structures comprising an oxidation catalyst; (xi) the reductioncatalyst comprising platinum and/or rhodium and the oxidation catalystcomprises platinum and/or palladium; (xii) the substrate element beingsubstantially nonporous; (xiii) temperature control elements being incontact with the reactor body; (xiv) the reactor body forming a catalystriser in a fluid catalytic cracking process; (xv) the micro-structuresof catalyst material comprising iron coated with platinum; (xvi) napthesbeing the reactant inputs; (xvii) the catalyst material comprising atleast one of nickel, platinum, cobalt, or iron.

Another embodiment is a catalyst reaction process comprising the stepsof: (a) providing a reactor comprising a substrate element having asurface and a plurality of elongated micro-structures of catalystmaterial attached to the substrate surface, the micro-structurescomprising: (i) a width of less than about 1 um; and (ii) a length atleast five times the width; (b) injecting at least two reactants intothe reactor such that at least a portion of the reactants contact thecatalyst material; and (c) reacting the reactants with the catalyst atabove ambient pressure. This embodiment could also include thealternative wherein the reactants are reacted with the catalyst at atemperature of less than about 200° F. and a pressure of less than about50 psig.

EXPERIMENTAL EXAMPLES Example I

A reactor 2 (shown schematically in FIG. 6) was fabricated from one inchOD autoclave tubing and was six inches in length. The catalystsubstrates were three ¼ inch diameter aluminum rods approximately twoinches in length. The rods 16 were allowed to rest on one another withno specific structure spacing the rods 16 apart. The reactor 2 wassealed on each end with standard “Swagelok®” compression fittings.

Micro-catalyst needles were formed on the substrate rods 16 with thefollowing process. First, the substrates 16 were mechanically cleaned.Using household cleaners (e.g., Lysol or Formula 409), the substrates 16were presoaked in the cleaner for approximately 20 minutes. Using a wirebrush or other abrasive cleaners, the substrates 16 were scrubbed toremove any mill scale or dirt. The substrates 16 were then returned tothe cleaning bath for 20 minutes. Second, a commercially availablealkaline cleaner was heated to 140° F. and the substrates 16 wereimmersed in the solution for 20-30 minutes. Third, the aluminumsubstrates 16 were chemically etched using a weak solution of sodiumhydroxide. This solution was maintained at approximately 110° F. Thesubstrates 16 were submerged in the solution for 20 seconds to oneminute. If the substrates 16 foamed excessively, they were removed fromthe solution. Fourth, the substrates 16 were deoxidized. Surface etchingtypically leaves behind some oxidized material or smut. This materialshould be removed before anodizing. Commercial aluminum desmuttingsolutions are recommended to accomplish this task. This example processused a commercial “Desmut AL-1” at a concentration of 9 ounces pergallon of solution. Immersion times vary due to the degree of oxidation,but generally were in the range of one to three minutes. Fifth,substrate anodization was conducted in a sulfuric acid solution at aconcentration of 8 ounces per gallon of solution. The solution was notheated, but was agitated. The substrates 16 to be micro-templated wereconnected to the anode terminal of a DC power supply and immersed in theacid solution. A cathode from the power supply was also immersed in thesolution. Substrates 16 were anodized with a current density of about0.1 A/in². DC potential typically ranged from 10 to 20 volts. Typically,a 20 minute anodizing process was used to produce the nano-structuredtemplate having micropores on the order of 10 nm.

Lastly, the catalyst micro-needles were formed on the substrate 16. Forpurposes of this example, cobalt was selected as the catalyst materialto be plated. The source of cobalt used was cobalt nitrate and asolution of two ounces CoNO₃ per gallon of solution was prepared. Thesubstrates 16 to be plated were immersed in the solution and connectedto a cathode of a DC power supply. The anode for the power supply wasconnected to another electrode and also immersed in the CoNO₃. A currentdensity of 0.050 A/in² with a DC potential of two to three volts. Thisprocess was continued for 2 to 8 hours to produce micro-needles about 10nm in diameter and 5 um in length with a packing density of about 30%.

The reactor tube 41 (with substrate rods 16 inserted) was placed on ahot plate 40 and connected to a source of reactant gases at one end ofthe tube and the opposite end of the tube was connected to a flask andproducts were collected at atmospheric temperature. Reaction gases wereobtained from cylinders provided by Nexaire® Gasses and were regulatedto approximately 450 PSIG and gas flow was controlled with “Aalborg”mass flow controllers. The reactor 2 pressure was maintained by a backpressure regulating valve obtained from “Swagelok”. The hot plate 40 waskept at about 400° F. After the catalyst was loaded, the reactor 2 waspurged to remove contaminants and then pressurized to 400 psig. A flowof hydrogen was established and the temperature was increased toapproximately 400° F. Carbon monoxide and hydrogen were introduced intothe reactor 2 at stoichiometric ratios and a reactor space velocity of0.14 min⁻¹ was achieved. Reaction gases flowed into the reactor 2reacted on the surface of the catalyst and the products exited thereaction space at high temperature (˜400° F.) and high pressure (˜400PSIG) in one phase. The reactor 2 was continuously operated in the abovedescribed regime for 13 days. There was cooling of the product when itexited the reactor 2 through the back pressure regulator and productcollection was at atmospheric temperature. After the pressure wasreduced in the backpressure regulator, the reaction products were cooledand the liquid/solid phases produced were collected. The denser phaseswere separated from the gasses in a single stage as the reactionproducts were collected. No evidence of charring or coking of thecatalyst micro-needles was seen. Analysis showed the CO conversion wasapproximately 0.045 mol CO/mol Co—min. FIG. 8 shows the hydrocarbonsproduced and their percentage distribution.

Example II

Another reactor was fabricated from one-half inch autoclave stainlesssteel tubing and was about eighteen inches long as suggested in FIG. 7.CO and H₂ reactants were supplied from cylinders and controlled at 450PSIG. Reactant flowrates were controlled by Aalborg® mass flowcontrollers 43. The reactants first passed through a preheater 44constructed of ¼ inch stainless steel tubing about 18 inches in lengthwith heating trace 45 wrapped around the tubing. The reactor tubelikewise was wrapped with heating trace 45. The reactor system alsoincluded a cascade temperature controller 46 and a Swagelokback-pressure regulator 48. Although not shown in FIG. 7, the reactorsystem included a separator which received the reacted product andremoved water from the hydrocarbons. A simple separator was formed witha five gallon glass carboy that separated the liquid products from thevapor products. The catalyst substrates were ¼ inch aluminum 6061-T6 allthread rods with cobalt micro-needles formed as described in Example I.

After four rods were inserted into the reactor and supported in thevertical position by the rod threads engaging compression fittings atthe reactor exit end, the other reactor end was sealed using “Swagelok”compression fittings. The flow controllers were set at 300 SCCM for COand 150 SCCM for H₂. The reactor temperature was controlled at 400° F.with the heating traces 45 and the pressure was regulated at 400 PSIGusing the back-pressure regulator 48. The temperature of the exitingfluid was measured using a thermowell and a “J” type thermocouple. Thistemperature was controlled by manipulating the reactor wall temperature(by cycling the heat tracing on/off) which was measured by a surfacethermocouple in a cascade mode. The product produced was a hydrocarbonmixture which consisted substantially of C—numbers that are normallyconsidered in the diesel range.

Example III

As suggested by FIG. 9, a multi-channel borosilicate microreactor 50 wasfabricated in order to conduct simultaneous testing of various forms ofcobalt catalysts. The top piece of the microreactor had channels 52etched via a polymer mask and sandblasting. The bottom piece of themicroreactor had a restive heater 53. See Brown, et al., Microreactorsfor Synthetic Diesel Production to Optimize Nanostructured CobaltCatalyst, Institute for Micromanufacturing, LA Tech University, 2009,which is incorporated by reference herein in its entirety.

Fabrication of the metal (e.g., Al) strips was performed via deposition,photolithography, and etching steps. Photoresist S1813 was used for thephotolithography portion of the fabrication. Process steps included a3000 rpm, 1 min photoresist spin, 115° C., 2 min anneal, and 90 sec ofUV exposure. The exposed Al from this process was etched with a solutionof 1 vol % HNO₃ (Sigma Aldrich, 70%, A.C.S. reagent), 10 vol % H₃PO₄(Alfa Aesar, 85% aq. soln.) with the remainder water and heated to 50°C. The undeveloped photoresist was removed with acetone.

A reference catalyst of cobalt was electroplated on one of the aluminumstrips. The plating solution consisted of a 100 g/L aqueous solution ofCoCl₂.6H₂O and was plated at a current density of 30 mA/cm2 at roomtemperature for 2 min using a cobalt counter-electrode.

A second test catalyst of cobalt was impregnated into the pores of Al₂O₃(alumina). The alumina was fabricated via anodization in oxalic acidfollowed by chromic acid etching. The anodization process typicallyproduces small pores with increasing diameter as the alumina increasesin thickness due to a steady drop of current density with constantvoltage. Therefore the process was modified by maintaining a constantcurrent density with a steadily increasing voltage yielding acylindrical shape rather than a conical shape. A high current densitywas used to increase the interpore spacing followed by etching inchromic acid to increase pore diameter to approximately 100 nm. Co(NO₃)₂was used as the aqueous cobalt source because of its high solubility of134 g/100 mL. The solution was deposited onto the porous aluminum oxidestructure and allowed to dry, thus allowing the metallic cobaltprecipitate to stick to the inside of the pores.

A third catalyst was a cobalt nanowire catalyst. The same anodization asperformed in the second catalyst was performed to obtain the porousaluminum oxide layer. Cobalt nitrate was used as the aqueous solution aswell. The solution consisted of 7.6 wt % cobalt nitrate at roomtemperature with a potential of 2 V. The cobalt was deposited under ahigh magnetic field produced by a neodymium-iron-boron (NIB) magnet witha BHmax of 50 MGOe. Once the cobalt nanowires extended beyond thealuminum oxide substrate the intrinsic magnetic field of the wires andthe NIB magnet continue to the keep the nanowires growing along the samecrystalline planes.

The resulting nanowires had a diameter similar to the pore size andtapering to a point at their maximum height on the order of 10 μmobtaining high-aspect ratio nanostructures determined by a Hitachi S4800scanning electron microscope (SEM) with an Edax Genesis energydispersive spectroscopy.

Hydrogen and carbon monoxide were flowed into the reactor at variablestoichiometric ratios and heated to a variety of operation conditionsranging from 150° C. and 300° C. and 300 psi to 450 psi. The cobaltcatalysts tested were in fixed bed reactor configuration. The liquidproduct formed in the channel with the magnetically formed nanowires at280° C. and 410 psi produced a liquid phase composed of 94% diesel.

The catalyst formed of nanowires ran for more than 300 hrs withoutshowing major signs of wear which is much higher than typical cobaltcatalysts that generally have a lifetime of no more than one hour.Oxidation is the primary reason cobalt catalysts deactivate and cokingis secondary. Coking is when multiple carbon atoms come together to formgraphite. The significantly longer run time is probably due to a highcrystallinity of the nanowires so oxygen in the reactant stream cannotpermeate into the cobalt structure via grain boundaries. The long runtime is also evidence that the open structure of the cobalt nanowiresdoes not allow for hydrocarbon accumulation as happens in a porouscobalt catalyst.

The invention claimed is:
 1. A Haber-Bosch process comprising the stepsof: (a) providing a reactor including substrate elements having catalystfilaments formed on the substrates elements, the catalyst filamentscomprising (i) a diameter of about 10 nm to about 500 nm; (ii) a lengthof about 30 nm to about 5000 nm; (iii) a packing density of between 5mg/cm2 and about 200 mg/cm2; and (iv) being formed of a metal includingiron; (b) injecting a nitrogen compound and hydrogen into the reactorsuch that at least a portion of the nitrogen compound and hydrogencontact the catalyst filaments; (c) reacting the nitrogen compound andhydrogen with the catalyst filaments at a temperature of less than about600° F. and a pressure of less than about 2000 psig.
 2. The processaccording to claim 1, wherein the nitrogen compound is N2.
 3. Theprocess according to claim 1, wherein the catalyst filaments compriseeither iron or iron with osmium layers.
 4. The process according toclaim 1, wherein the reaction pressure is less than about 1250 psig. 5.The process according to claim 1, wherein the reaction pressure is lessthan about 1000 psig and the reaction temperature is between about 250°F. and about 450° F.
 6. The process according to claim 1, wherein thesubstrate elements are substantially nonporous.
 7. The process accordingto claim 1, wherein the filaments packing density is at least about 20mg/cm2.
 8. The process according to claim 1, wherein the substrateelements are formed of a conductive material.
 9. The process accordingto claim 1, wherein the substrate elements are a nonconductive materialwith a layer of conductive material applied thereto.
 10. The processaccording to claim 1, wherein the catalyst filaments have a diameterbetween about 10 nm to about 200 nm.